Operation of Power Diodes at Cryogenic Temperature

International audiencePower converters working at cryogenic temperature (Cryo-converters) can present several advantages, so studies related to this area has been of great interest to the aviation sector [1], notably if the refrigeration system is considered as free of charge as currently envisaged in the future aircraft. This paper deals with the diode bridge operation maintained at a cryogenic temperature (77°K). Measurements carried out on different power diodes show that the electrical characteristic differs from one diode to another in the bridge at room and cryogenic temperature. These tests show that different types of diode technology are more conducive to operation at cryogenic temperatures than others. For example, the BYT60-400 diode tested in the laboratory has a higher dynamic resistance and threshold voltage at cryogenic temperature than in room temperature (Figure 1a) when in comparison with the APT2X101D120J (Figure 1b). This result is coherent with the literature [2]. It is therefore essential to choose the best diode for the desired application. Continuing, using only the APT2X101D120J diode, a 97 kW three-phase diode bridge was simulated in MATLAB/Simulink to compare the operation at the two temperatures using the diode characteristics obtained in the previous measurements. The simulation showed that a power gain of 80 W can be obtained by considering only the electrical characteristic of the diode and that the cooling is provided free of charge. Considering these advantages, the next step will be to carry out a technical-economic analysis to compare both solutions in terms of their life cycle